Electric switch



y 1946. G. w. GLOVER 2,399,920

- ELECTRIC SWITCH F- iled Sept. 25, 1944 Fig.1.

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y His Attorney.

Patented May 7, 1946 ELECTRIC swrrcn George W. Glover, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application September 25, 1944, Serial No. 555,655

3 Claims.

My invention relates to electric switches, more particularly to electromagnetically operated switches of the type known as contactors, and has for its object simple, reliable and inexpensive means for preventing the closure of the switch by heavy, shocks.

In carrying out my invention in one form, I provide a small shock responsive member made of an electrically insulating material which is carried on the movable switch member and which is normally biased by gravity to a position in which it does not interfere with the closure of the switch. This member is slidably mounted for movement lengthwise of the movable switch member in such manner that it is moved by a shock applied to the switch in front of the movable switch contact so as to be interposed between it and the stationary contact and prevent closure of the switch by the shock. V

For a more complete understanding of my invention,- reference should be had to the'accompanying drawing, Fig. l of which is a side elevation view of an electromagnetically operated switch or contactor embodying my invention; Fig. 2 is a fragmentar side elevation View partly in section showing the shock responsive memher in its switch closure preventing position;

- whil Fig. 3 is a fragmentary front elevation view partly broken away showing. the parts in the same relative position as Fig. 2.

Referring to the drawing, I have shown my invention in one form as applied to a contactor comprising a U-shaped magnet core I, one arm of which is a cylinder and provided with a pole face 2 for a pivoted armature 3. An operating coil 4 is mounted on the cylindrical core arm, the core member being mounted on a panel support 5 made of electrically insulating material. The armature 3 made of magnetic material is pivot ally mounted on its lower edge 6 on a plate 1 ecured to the lower side of the magnet core I. A central portion 8 of the plate I is bent downward to provide a support for a spring biasing pin 9 which extends through a hole in the portion 8 and through a hole in the bracket member ID secured to the armature. The armature is biased by a helical spring surrounding the rod 9 and having one end engaging a seat |2 on the rod, and its other end engaging the bracket l0. Thus the spring applies a compression force normally biasing the armature to its unattracted position shown.

When the coil 4 is energized, the armature moves about its pivot 6 into engagement with the pole face 2 except for an air gap provided by the shim |3 made of non-magnetic material, such as brass. In moving to its attracted position, the armature moves a movable contact M on its upper movable end into engagement with a stationary contact l5. This stationary contact ,is mounted on a bracket IE secured to the panel 5. A blowout coil I1 is mounted on the bracket l6 which is connected by a conductor l8 between the terminal l8 and the support Hi to which the opposite end of the blowout coil is electrically connected, the stationary contact I5 being also electricallyconnected with the support IE, A suitable are chute l9 made of electricall insulating, heat refractory material is provided for the contacts with a magnetic pole plate 20 on each side associated with the blowout coil whereby a magnetic field is provided across the arc chute.

In accordance with my invention, I provide a shock responsive or inertia member 2| made of an electrically insulating, heat refractory materiaLsuch as a hard fibre, which is mounted on the armature 3 in a position normally, as shown in Fig. l, with its upper end just below the movable contact |4 so as to offer no interference with the engagement of the contact M with the stationary contact l5 whensthe coil 4 is energized. This shock responsive member 2| is mounted for slidable movement lengthwise of the armature away from the pivot of the armature so that, in the event of a shock applied to the support 5 and the switch, when the switch is open and the armature 3 in its unattracted position, the member 2| is thrown upward to the position shown in Figs. 2 and 3 from its gravity biased position by any component of the shock tending to move the armature toward its attracted position. The member 2| has a very small inertia as compared with the inertia of the armature and the switch contact and other parts carried by it, and, as a result, its movement in response to a severe shock from its lowermost unlatched position shown in Fig. 1 to its uppermost latched position shown in Figs. 2 and 3 is faster than the movement of the armature toward its attracted position. Moreover, the member 2| moves only a short distance to its interference position of Figs. 2 and 3 as compared with the movement of the armature to its closed circuit position. As a result, the member 2| is thrown upward to the interference posi tion of Figs, 2 and 3 by any component of a shock force which throws the armature toward its attracted position. In this interference position the upper end of the member 2| is in front of the contact engaging face of the movable contact, 1. e.,

between the contacts, and thereby prevents closure of the switch by a shock. It will be understood that when the switch is closed by the coil 4 the member 2| remains in the lowermost position Referring to additional details of construction, the movable contact I4 is mounted on a short arm 22 which normally is held by a compression spring 23 against a plate 24, the lower end of which is secured by screws 25 to the upper end of the armature. Thus the armature and arm 22 together constitute a pivoted switch arm. The shock responsive member 2| is secured to the right-hand side of the plate 24 by means of a bar 26 made of electrically insulating material which is secured to the upper end of the plate 24, in transverse relation therewith. This bar has a notch cut in its right-hand side, as seen in Figs. 1 and 2, through which the member 2| extends. As shown in Fig. 2, this notch is considerably deeper horizontally than the thickness of the member 2|, there remaining a relatively thin portion 21 of the bar 26 at the bottom of the notch. Moreover, the notch is somewhat wider than the member 2|, 1. e., in a horizontal direction as seen in Fig. 3. On the right-hand side of the bar 26, as seen in Figs. 1 and 2, is secured a plate 28 which extends across the notch in the bar and forms a right-hand wall for the notch. The lower end of the plate 28 has a portion 29 bent over toward the left hand on which the member 2| normally rests in accordance with its gravity bias. A semicircular notch is provided in the upper end of the plate 28 for the purpose of increasing the electric clearance with respect to the stationary contact. Also, at its lower end the member 2| is provided with laterally extending projections 30 and 3| which engage the side walls of the slot when the member is thrown to its uppermost position, as seen in Figs. 2 and 3.

As shown, an electric connection can be made with the movable contact M by means of a termina1'32 which is actually a bolt securing the magnet core I to the panel 5. From the magnet core I a flexible conductor 33 extends to the member 22 on which the movable contact is mounted.

While I have shown a particular embodiment of my invention, it will be understood, of course,

that I do not wish to be limited thereto, since many modifications may be made and I, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A switch comprising amovable switch member provided with a movable contact, a stationary contact engageable by said movable contact, and an inertia member made of electrically insulating material movably mounted on said switch. member and biased to a predetermined position to provide for normal movement of said movable contactv into engagement with said stationary contact but moving in response to a shock applied to said switch to a position between said contacts thereby to prevent the engagement of said contacts by the shock.

2. A switch comprising a movable support, a movable contact on said support, a stationary contact engageable by said movable contact upon movement of said support, a member made of electrically insulating material mounted on said support for movement over the face of said movable contact, said member being normally biased out of engagement with said contact face but moving in response to a shock applied to said switch to a position over said contact face thereby to prevent the engagement of said contacts by a shock.

3. A switch comprising a pivoted arm, a movable contact on the movable end of said arm, a stationary contact engageable by said movable contact, means for moving said arm on its pivot to move said movable contact into engaged and disengaged relation with said stationary contact, and an inertia member made of electrically insulating material mounted on said contact arm for slidable movement lengthwise of said arm over the face of said movable contact, said inertia member being normally biased toward the pivot of said arm into a position out of engagement with said contact but moving in response to a shock applied to said switch to a position over said contact face thereby to prevent the engagement of said contacts by a shock.

GEORGE W. GLOVER. 

